The default behavior is to kill all eligible and unkillable threads until 
there are none left to sacrifice (i.e. all kthreads and OOM_DISABLE).

 
In a simple test with virtualbox, I reduced the amount of ram to 300MB. 
Then I ran "swapoff -a" and opened some applications. I noticed that the free
spaces is kept around 2-3MB and "kswapd" is running. Also I saw that disk
activity was very high. 
That mean although "swap" partition is turned off, "kswapd" was trying to do
something. I wonder how that behavior can be explained?

Ok, so you don't have a /proc/pid/oom_score_adj, so you're using a kernel 
that predates 2.6.36.

Yes, the srv machine that I posted those results, has kernel before 2.6.36



// Naderan *Mahmood;


----- Original Message -----
From: David Rientjes <rientjes@google.com>
To: Mahmood Naderan <redacted>
Cc: Randy Dunlap <redacted>; ""linux-kernel@vger.kernel.org"" <redacted>; "linux-mm@kvack.org" <redacted>
Sent: Thursday, August 11, 2011 8:39 AM
Subject: Re: running of out memory => kernel crash

On Wed, 10 Aug 2011, Mahmood Naderan wrote:

quoted

If you're using cpusets or mempolicies, you must ensure that all tasks 
attached to either of them are not set to OOM_DISABLE.  It seems unlikely 
that you're using those, so it seems like a system-wide oom condition.

 
I didn't do that manually. What is the default behaviour? Does oom
working or not?

The default behavior is to kill all eligible and unkillable threads until 
there are none left to sacrifice (i.e. all kthreads and OOM_DISABLE).

For a user process:

root@srv:~# cat /proc/18564/oom_score
9198
root@srv:~# cat /proc/18564/oom_adj
0

Ok, so you don't have a /proc/pid/oom_score_adj, so you're using a kernel 
that predates 2.6.36.

And for "init" process:

root@srv:~# cat /proc/1/oom_score
17509
root@srv:~# cat /proc/1/oom_adj
0

Based on my understandings, in an out of memory condition (oom),
the init process is more eligible to be killed!!!!!!! Is that right?

init is exempt from oom killing, it's oom_score is meaningless.

Again I didn't get my answer yet:
What is the default behavior of linux in an oom condition? If the default is,
crash (kernel panic), then how can I change that in such a way to kill
the hungry process?

You either have /proc/sys/vm/panic_on_oom set or it's killing a thread 
that is taking down the entire machine.  If it's the latter, then please 
capture the kernel log and post it as Randy suggested.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>